One of the main concerns for fish processors is unwanted bones in fish fillet, such as whitefish in particular cod. Beside that such bones make the fish product less attractive it can have devastating effect if they are swallowed. This can have negative publicity, which may lower the value of the product. Therefore it should not surprise anyone that fish producers all over the world spent much effort in finding bones and removal them. This is and been very labour consuming operation, where some of the bones are difficult to find and to remove. In some cases a part of the fish fillet must be removed due to difficulties in removal the bones.
Apparatus for processing fish exist. In U.S. Pat. No. 5,525,101 a device is described for removal bones from fish meat. This device is however hand-held device, which means that the processing in operating the fish product is mainly controlled by the worker. Further this it is a demanding job to hold the device in hand with its electrical power supply. As the device is hand-held the possibilities to automate the process are very limited.
From a Danish utility Model DK 1999 00226 U4 an apparatus is presented for bone removal, where the apparatus is hinged to a frame above a conveyor. The bone-removal unit is then elevated semi- or fully automatically toward the upwardly facing surface of the fish filets and driven over the entire surface. The problem with this method is that the entire surface is brought into contact with the bone-removal unit, which can damage the fish fillet.
An improved apparatus and method for removal bones is presented in WO 01/43553, that comprises a conveyor and a bone-removal unit hinged above the conveyor, where the bone removal unit is movable in an approximated up-and downward direction toward the conveyor. The conveyor comprises an upwardly extending edge and a plurality of elevating means forming a horizontal support for the fish fillet there in-between for elevating a particular area of the fillet. On the outside of said elevating means a pressure means or device is provided to maintain the fish in a fixed position. The bones are removed by bringing the removal units into contact to that particular area to that are primarily located in the horizontal surface.
The main problem in WO 01/43653 is that the bones to be removed are not sufficiently exposed because of the horizontal support for the bone-removal unit, which may result in that some bones are left in the fish after the processing. Also, the movement of the bone-removal unit is limited to only up-and downward movement, and therefore bones that are not in the plane of the bone removal unit remain in the fish fillet. Further, the pressure means that is provided for maintaining the fish fillet in a fixed position may be reduced to the interval where the bones removal procedure is running, which would simplify the apparatus significantly.